Incandescent lamp.



URAFTSMKN J'. W. HOWELL.

INGANDESGENT LAMP.

APPLICATION FILED NOV.17, 1906.

Patented Nov. '17, 1908.

FIE.

INVENTDR WITNEEEIEEJ:

L L E W U W N H m J Lo V W v. A f Q U IN 11. a. EAAIES T OFIOE.

JOHN HOWELL, OF NEWARK, NEW JERSEY, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

INGANDESCENT LAMP.

Specification of Letters Patent.

Patented Nov. 17, 1908.

Application filed November 17, 1906. SeriaINo. 343,832.

This invention relates to incandescent electrio lamps and processes for their manufacture, and comprises a new method of sealing the lamp filaments to the leading-in wires.

Incandescent lamp filaments of tungsten, tantalum, niobium, titanium and other refractory metals, alloys and compounds have operating temperatures considerably higher than that of the ordinary type of carbon filament, consequently the methods of securing filaments to the leading-in wires in lamps of the carbon type are not generally applicable to these more refractory materials.

According to my invention, the filament, say of tungsten, is welded directly to the lead-wire. The joint is made without the use of any paste or binding material which might contain moisture, carbon or other components possibly injurious to the filament at its exceedingly high running temperature.

The welded joint between the lead-wire and the filament, is produced by melting down the end of the lead-wire into a compact globule or bead within which the lamp filament is embraced.

The fusing or welding operation is performed electrically and in a protective atmosphere, as hereinafter described in detail.

Figure 1 is a diagrammatic representation of the apparatus used for producing the welded joint; Fig. 2 is an enlarged View of one of the leading-in wires, showing the position of a filament end with respect to the leading-in wire before the welding operation is performed; Fig. 3 is an enlarged View of the completed joint.

The apparatus shown in Fig. 1 consists of a glass jar 1, to the bottom of which is secured an upright standard 2 provided with a clip 3 for engagement with the stem 4 of a lamp so that the stem is held rigidly in a horizontal position. A small tube 5 extends downward to the bottom of the glass jar and serves as a means for conducting carbon dioXid or other inert gas into the jar, where it acts as a protective medium during the sealing operation. A second tube 6, of copper or other suitable material extends downward into the jar and then bends up in a semicircle 7 and is provided with small openings 8 so disposed that when the gas is supplied to the tube it will escape through these openings and impinge on the ends of the leadingin wires. The gas so supplied may be hydrogenor other reducing gas, but I prefer to "i ise illuminating gas, as I have found this to be well adapted for the purpose.

Carbon dioXid is much heavier than air, and consequently the jar or vessel 1 remains constantly full, much as if a liquid were supplied through the tube 5. The illuminating gas, jetting upward through the heavy carbon dioXid, forms a reducing atmosphere in the immediate vicinity of the lead-wires, and is protected from oxidation by the carbon dioxid, through which it escapes to the outer air.

The electrical fusion or welding is effected by means of a source of current 9 and two portable electrodes 10 and 11, the former of copper or other metal, and the latter of carbon or graphite. Each of the lead-wires 12, is bent up at its end to form a hook 13 as clearly shown in Fig. 2. Within this hook is placed one end of the tungsten or other metal filament 14 and the operator then touches terminal 10 to the lead-wire, and terminal 11 to the end of the hook to establish a flow of current through the hook.

hook and form a globule by the direct heat ing action of the current flowing through the hook, but I prefer to melt down the hook by the heat of an are produced between the hook and the carbon electrode 11. This are may be readily established by first touching the carbon to the hook and then removing it. The current necessary to produce the weld depends on the size of the leading-in wire, but two or three amperes will give good results for lead-wires of usual diameter.

Fig. 3 shows the completed joint and illustrates the bead or globule 15 built on the end of the leadingin wire and securely welded to the end of the refractory filament.

In a divisional application, Serial No. 398,736, filed October 23, 1907, claims are made on the apparatus disclosed in the present application.

WVhat I claim as new and desire to secure by Letters Patent of the United States, is,

1. The process of securing a refractory This flow may be sufficient to fuse down thefilament to a current supply wire, which consists in electrically welding the filament to the Wire in a reducing atmosphere, and simultaneously protecting said reducing atmosphere from oxidation by means of an inert fluid.

2. The process which consists in welding an incandescent lamp filament to a wire by fusing down a portion of the wire within a protective envelop of fluid heavier than air.

3. The method of securing an incandescent lamp filament to a conductor by heating said conductor with electrical energy in a reducing atmosphere inclosed in carbon dioxid.

&. The method of securing an incandescent lamp filament to a conductor, which consists in drawing an arc from the end of said conductor to produce a bead of metal JOHN TV. HOWELL.

Witnesses J. H. ELKINs, GEO. V. DELANEY.

m in 

